Weep No More! Coatings Team Tames Oozing Oil

By  Jack Innis

When the team from A&G Industrial Services arrived on scene, it was not difficult to pinpoint the problem. Two 45,000-gallon concrete underground fuel oil bunkers at the New Hampshire power plant were weeping in a big way.

Oil seeped from the 50-year-old bunkers so badly that in summertime, when ambient temperatures ran high, the stored fuel would seep up through the power plant’s concrete floors, forming unstoppable rivulets of ooze — not good for workers or the environment.

But these were not containment vessels that the power plant could easily take off line for repair. Called “Day Tanks,” these bunkers store just the right amount of fuel oil for the plant to burn in one business day.

It was Christmas Day when the power company decided to drain the 50' long, 10' wide, and 12' high tanks for steam cleaning and inspection. When they drained the first tank, what they found was disturbing. Huge cracks and holes in the concrete tank’s otherwise-bare walls had been filled and coated in the past. That coating had failed, causing the seepage. The utility company called their go-to coating team, A&G Industrial Services.

Into The Inferno
A&G’s Peter Krukiel knew his team would face multiple challenges to get these tanks coated correctly. To start, A&G reviewed safety procedures. Two of the five-man crew would act as topside monitors at the 36" inspection hatch whenever anyone was in the tank.  Miller-brand harnesses, fall limiters, and a retrievable tripod were brought to the site and made ready. An MSA-brand continuous atmosphere monitor was put in place. A&G even had a scuba tank standing by in case one of the topside crew had to enter during an emergency.

“The first problem we found was that it was still 113ºF inside,” Krukiel said. “It was nuts to work in.” Day tanks store oil at 129ºF so it can burn more efficiently when it reaches the generators. The two tanks shared a common wall between them, so the empty tank was drawing heat from the full one. With only a few days down time available, there was no time to wait for the temperature to come down.

The contrast with the frigid New England winter outside the tanks was striking. While men working inside the bunkers sweated in Marco-brand cold vests and North-brand fresh-air masks, men working topside shivered in 5ºF New Hampshire weather.

Before they could tackle the oozing oil, the A&G crew had to remove some extremely stubborn existing coating from the cracks in the bunker. The team attacked the coating with Snap On-brand pneumatic air hammers with 6" chisel blades.

After chiseling off the old coating, Krukiel and crew needed to decontaminate the oily walls. Although a cursory job had been done earlier by an environmental company hired by the plant owner, it was plainly not sufficient. 

Not Clean Enough
“We knew it was nowhere near clean for our purposes,” Krukiel said. So using long-handled bristle brushes and plenty of elbow grease, the crew attacked the walls, ceiling, and floor with Zep-brand Industrial Citrus Cleaner. The crew sprayed the surfaces with low-pressure, hand-pumped, bug-type sprayers, then scrubbed. Each bunker required approximately 55 gallons of citrus cleaner.
As the men scrubbed, the citrus and oil mixture flowed down onto absorbent cleaning pads stacked around the tanks’ perimeter. The pads—2,500 in all for the project—and other waste materials were turned over to the plant operators for disposal.
Cleaned of oil, the first tank’s walls, floor, and ceiling were ready for abrasive blasting. Mike Rudnicki is A&G’s blast specialist. He used a medium-grit Black Beauty coal slag supplied with a 375 cfm SullAire-brand air compressor passing through a #7 tip.
After blasting, the crew bucketed up the slag and every square inch of the tank surface was vacuumed twice.

Finger In The Dike
While most tanks would have been ready for primer, the A&G team knew they still faced a serious challenge. How could they keep oil from seeping back through the cracks and ruin the coating’s adhesion?

Using a laser temperature gauge, they determined the wall was still 119ºF — a temperature that would certainly foster seeping. So they quickly filled the cracks with Duromar-brand Durostick, a two-part putty designed for making fast repairs on a variety of substrates. At normal temperatures, Durostick hardens in five minutes. On the hot bunker walls, it was rock hard in three.

With Durostick acting as an oil dam, the crew applied a more workable putty. They used Duromar SAR ceramic putty because of its resistance to chemical attack. The crew trowelled down the two-part putty in a succession of layers, filling the cracks level with the bunker walls.

Then A&G was ready to lay down Duromar HPL-1302 primer. The two-component amine hardened epoxy may be brushed, sprayed, or rolled. Since the concrete substrate was riddled with bug holes, A&G decided to roll with ¾" nap rollers.

To control ambients, a dehumidifier was brought in to pump dry air into the tank. An air conditioner, ordered early on in the project, finally arrived to help bring the ambients in line and make the men more comfortable.  “That brought the air temperature down to 92ºF,” said Krukiel. “The guys who did the prep work on the first tank wished the air conditioner had arrived sooner. It was brutal.”
Glass Walls
After the tank was primed, the crew pressed 3' woven fiberglass cloth strips into the coating. The strips were cut to size and applied from bottom to top, just like wallpaper, onto the still-gummy primer. Nine-inch rollers wetted the fiberglass and worked the air out.

After about six hours, the primer and fiberglass cloth set up. A&G had formed a tank within a tank. The crew then rolled on two, 20-mil layers of Duromar’s HPL 2510, 100% solids, amine-cured epoxy.

“We use this epoxy because it is immersion resistant, chemical resistant, it hardens really well, but has flexibility to it,” said Krukiel. “So even though it’s a hard as a rock, you could take a piece of it and bend it if you had to.”

The coatings crew alternated red and gray so that the colors helped show voids. Any pinholes were filled with a thin coat of SAR.

The crew washed the tank’s interior with acetone between coats. “We don’t want amine blush,” Krukiel said. “Although we do amine blush tests, which didn’t show up any high concentrations, we know this tank couldn’t fail. So for an extra hour with two guys, we gave ourselves a little extra protection.” 
   
After the first tank was finished and brought into service, the second tank was drained and the process repeated.

The project began the day after Christmas and ended January 5. They battled heat, cold, and seeping oil. But their efforts helped bring the client’s power generators back on line, and they are proud to have kept power going to New Hampshire’s lights and furnaces.

Sure, it was a tough job. But don’t weep for them, they’re coating professionals.

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